Table 1 Summary of the above ground instrument’s specifications.

Wind speed (WS)

Davis Instruments DVI7911

24

0.5 ms⁻¹ to

89 ms⁻¹

1 ms⁻¹ or 5%

0.1 ms⁻¹

Solid state magnetic sensor.

U-wind (U)

Campbell Scientific CSAT3

1

−60 ms⁻¹ to

60 ms⁻¹

Offset 0.08 ms⁻¹

Gain 2%/3%/6%

for wind within 5°/10°/20° of horizontal

0.001 ms⁻¹

3D sonic anemometer.

Set at sample rate of 60 Hz.

V-wind (V)

W-wind (W)

−8 ms⁻¹ to 8 ms⁻¹

Offset 0.04 ms⁻¹

0.0005 ms⁻¹

Air temperature (T)

Vaisala HMP60

24

−40 °C to 60 °C

• 0.5 °C when

     10 °C < T < 30 °C

• 0.6 °C when

−40 °C < T < 10 °C or

30 °C < T < 60 °C

0.1 °C

Relative humidity (RH)

0% to 100%

If 0 °C < T < 40 °C

• 3% (RH) when

0% < RH < 90%

• 5% (RH) when RH > 90%

If −40 °C < T < 0 °C

• 5% (RH) when

0% < RH < 90%

• 7% (RH) when RH > 90%

0.1% (RH)

Downward longwave radiation (DLW)

KippZonen CNR4

2

−250 Wm⁻² to

250 Wm⁻²

of net radiation between the sensor and the external source

• Non-linearity < 1%

• Temperature dependence < 4% when

−10 °C < T < 40 °C

• Tilt error < 1%

• Offset < 6 Wm⁻²

• Non-stability < 1%

• Spectral selectivity < 5%

Total uncertainty < 10% of the daily total

<0.1 Wm⁻²

Wavelengths between 4.5 and 42 𝞵m, field of view 180° (150°) for downward (upward).

Offset due to LW emitted by the sensor is accounted for using an internal thermistor.

Upward longwave radiation (ULW)

Downward shortwave radiation (DSW)

0 Wm⁻² to

2000 Wm⁻²

• Non-linearity < 1%

• Temperature dependence < 4% when

−10 °C < T < 40 °C

• Tilt error < 1%

• Offset < 15 Wm⁻²

• Directional error < 20 Wm⁻²

• Non-stability < 1%

• Spectral selectivity < 3%

Total uncertainty < 5% of the daily total

<0.1 Wm⁻²

Wavelengths between 0.3 and 2.8 μm.

Field of view 180° (150°) for downward (upward).

Upward shortwave radiation (USW)